Javascript Module Design

I've been trying to create a tree module in JavaScript for implementing a "family tree" style structure. I'm not very experienced in newer JavaScript design styles and want to make sure I am going along the right path with the code I have written so far. Can someone let me know if I am on the right track with how this is organized?

var TREE = (function() {

var treeList = [], //Tree container

    //Constructor for Member object
    Member = function(name, mother, father, children){
        this.name = name || null;
        this.mother = mother || null;
        this.father = father || null;
        this.children = children || null;
    },

    //Constructor for Tree object
    Tree = function(name){
        this.name = name || null;
        this.memberList = [(new Member("root"))];
    };

//Tree methods  
Tree.prototype.addMember = function(name, mother, father, children){
    this.memberList.push(new Member(name, mother, father, children));
}
Tree.prototype.getMemberList = function(){
    return this.memberList;
}
return {
    create : function(treeName){
        treeList.push(new Tree(treeName));
        return treeList[treeList.length - 1];
    },
    getTreeList : function(){
        return treeList;
    }
};

}());